<p>
  <app-child uname="tom"></app-child>
  <app-child [uname]="uname" #child></app-child>

  <app-child *ngFor="let name of names" [uname]="name"
             (change)="onchange($event)"></app-child>

  <input type="text" #inp>
  <button (click)="uname=inp.value">变更</button>
</p>
<div>{{child.uname}}</div>

<app-child2></app-child2>
